Augmented synthetic control report, single treatment

Author

Simone Wien

Overview

This repository provides code and sample data to estimate the effect of single state’s policy on birth outcomes using the augmented synthetic control method (ASCM) utilizing the augsynth package. This report displays select results and their corresponding diagnostic tables and plots.

The policy exposure in this example is Texas Senate Bill 8 (TX SB 8), a 6 week gestational ban on abortion that went into effect on September 1, 2021.

All results are generated using synthetic data and therefore are for educational purposes only.

Cohort definition

Inclusion criteria

  1. All births and fetal deaths beginning January 1, 2014

Exclusion criteria

  1. Singleton births and fetal deaths
  2. Gestational age \(\geq\) 20 weeks
  3. Removed Connecticut records due to undercounting of fetal deaths
  4. Removed Virginia due to record quality (maternal morbidity outcomes only, not shown in this report)

Exposure definitions

Exposure 1: policy implemented by at least 6 weeks gestation

Pregnancies are exposed if, by the date the policy went into effect, the pregnancy was at least 6 weeks gestational age.

  • Pregnancies where the stillbirth or birth occurred before the policy went into effect are unexposed
  • Pregnancies that were under 6 weeks gestational age by the date the policy went into effect are removed from the analysis (i.e., only looking at the first cohort of pregnancies)

Due to the nature of preterm births, for this exposure definition observations on or before April 1, 2022 for this analysis need to be removed.

Exposure 2: policy implemented at any time during pregnancy

Pregnancies are considered exposed if the policy was in effect for any portion of the pregnancy.

  • Pregnancies where the stillbirth or birth occurred before the policy went into effect are unexposed
  • No additional pregnancies are removed

Due to other states receiving the treatment (i.e., causing unbalanced data) the post-treatment period ends at May 1, 2022.

Outcomes

  1. Stillbirth rate
  2. Preterm birth rate, conventional approach: live births are only included in the denominator
  3. Preterm birth rate, “fetus-at-risk approach”: live births and stillbirths are included in the denominator

Time-varying confounders

  1. State Medicaid expansion
  2. State proportion of pregnancies where maternal age \(\geq\) 35 at the time of the stillbirth or birth

Results and ASCM diagnostics

Exposure 1: policy implemented by at least 6 weeks gestation

Stillbirth

Stillbirth ATT
Time Estimate Lower CI Upper CI p value
0 0.036 -0.170 0.242 0.824
1 0.154 -0.052 0.360 0.355
2 0.138 -0.068 0.344 0.351
3 -0.129 -0.335 0.077 0.408
4 -0.016 -0.222 0.190 0.933
5 -0.027 -0.233 0.179 0.847
6 -0.112 -0.318 0.094 0.509
Stillbirth observed and synthetic summary
Observed
Synthetic
Period Months Mean SE Lower CI Upper CI Mean SE Lower CI Upper CI
Post-Policy 7 0.515 0.035 0.429 0.60 0.508 0.023 0.452 0.565
Pre-Policy 92 0.527 0.016 0.495 0.56 0.527 0.007 0.514 0.541
Stillbirth RMSE
Average ATT Pretreatment RMSE
0.006 0.138

Preterm birth, conventional approach

PTB ATT
Time Estimate Lower CI Upper CI p value
0 0.276 -0.359 0.912 0.492
1 0.128 -0.507 0.763 0.755
2 -0.181 -0.816 0.455 0.688
3 0.559 -0.076 1.194 0.081
4 0.218 -0.417 0.853 0.647
5 -0.104 -0.740 0.531 0.893
6 0.459 -0.177 1.094 0.241
PTB summary
Period Time Points Observed mean Observed SE Observed Lower CI Observed Upper CI Synthetic mean Synthetic SE Synthetic Lower CI Synthetic Upper CI
Post-Policy 7 11.739 0.219 11.203 12.275 11.545 0.210 11.030 12.060
Pre-Policy 92 11.080 0.083 10.916 11.245 11.080 0.072 10.938 11.223
PTB RMSE
Average ATT Pretreatment RMSE
0.194 0.296

Preterm birth, fetus-at-risk approach

PTB FAR ATT
Time Estimate Lower CI Upper CI p value
0 0.281 -0.355 0.916 0.416
1 0.142 -0.493 0.778 0.742
2 -0.179 -0.815 0.456 0.714
3 0.570 -0.065 1.206 0.088
4 0.215 -0.421 0.851 0.633
5 -0.121 -0.757 0.515 0.899
6 0.436 -0.200 1.072 0.230
PTB FAR summary
Period Time Points Observed mean Observed SE Observed Lower CI Observed Upper CI Synthetic mean Synthetic SE Synthetic Lower CI Synthetic Upper CI
Post-Policy 7 11.703 0.217 11.173 12.234 11.511 0.204 11.013 12.010
Pre-Policy 92 11.033 0.083 10.868 11.197 11.033 0.072 10.891 11.175
PTB FAR RMSE
Average ATT Pretreatment RMSE
0.192 0.295

Exposure 2: policy implemented at any point in pregnancy

Stillbirth

Stillbirth ATT
Time Estimate Lower CI Upper CI p value
0 -0.396 -0.797 0.000 0.054
1 0.227 -0.109 0.546 0.239
2 0.134 -0.217 0.470 0.412
3 0.298 -0.070 0.667 0.135
4 0.032 -0.353 0.433 0.818
5 0.058 -0.326 0.443 0.769
6 0.040 -0.345 0.441 0.849
7 0.007 -0.377 0.375 1.000
Stillbirth observed and synthetic summary
Observed
Synthetic
Period Months Mean SE Lower CI Upper CI Mean SE Lower CI Upper CI
Post-Policy 8 0.648 0.070 0.484 0.813 0.598 0.014 0.565 0.632
Pre-Policy 92 0.568 0.018 0.533 0.603 0.568 0.007 0.554 0.581
Stillbirth RMSE
Average ATT Pretreatment RMSE
0.05 0.139

Preterm birth, conventional approach

PTB ATT
Time Estimate Lower CI Upper CI p value
0 0.277 -0.487 1.041 0.480
1 0.138 -0.626 0.902 0.747
2 -0.148 -0.913 0.616 0.801
3 0.577 -0.125 1.341 0.099
4 0.226 -0.538 0.990 0.652
5 -0.031 -0.795 0.733 0.987
6 0.772 0.000 1.536 0.069
7 0.263 -0.501 1.027 0.645
PTB observed and synthetic summary
Observed
Synthetic
Period Months Mean SE Lower CI Upper CI Mean SE Lower CI Upper CI
Post-Policy 8 12.101 0.144 11.762 12.441 11.842 0.089 11.632 12.052
Pre-Policy 92 11.080 0.083 10.916 11.245 11.080 0.072 10.937 11.223
PTB RMSE
Average ATT Pretreatment RMSE
0.259 0.298

Preterm birth, fetus-at-risk approach

PTB FAR ATT
Time Estimate Lower CI Upper CI p value
0 0.279 -0.481 1.040 0.505
1 0.151 -0.610 0.881 0.737
2 -0.146 -0.906 0.615 0.765
3 0.585 -0.175 1.346 0.078
4 0.237 -0.524 0.998 0.633
5 -0.035 -0.796 0.725 0.982
6 0.755 -0.006 1.516 0.074
7 0.255 -0.506 1.015 0.637
PTB FAR observed and synthetic summary
Observed
Synthetic
Period Months Mean SE Lower CI Upper CI Mean SE Lower CI Upper CI
Post-Policy 8 12.055 0.143 11.717 12.394 11.795 0.088 11.586 12.004
Pre-Policy 92 11.033 0.083 10.868 11.197 11.033 0.072 10.890 11.175
PTB FAR RMSE
Average ATT Pretreatment RMSE
0.26 0.297